OTTAWA, May 15 (Reuters) - Canadian manufacturing sales, pushed up by gains in the aerospace and auto sectors, rebounded by 2.9 percent in March from February after big falls the previous two months, Statistics Canada said on Friday.

The month-on-month increase in March was the largest since the 3.3 percent jump recorded in July 2011.

Output in the volatile aerospace industry jumped by 42.3 percent in March after dropping 29.4 percent in February. Most contracts are in U.S. dollars and a weaker Canadian dollar in March boosted the value of production.

Factory sales of motor vehicles grew by 12.8 percent as auto plants came back on stream after shutdowns for retooling in the first two months of the year.

Overall, sales rose in 10 of 21 industries, representing about 60 percent of all Canadian manufacturing. Constant dollar sales rose 2.9 percent, a sign the volume of goods sold in March also increased.